In recent years, with the expansion of the application of rechargeable batteries, such as lithium-ion batteries, a larger capacity and a higher energy density have been required, so that a layered battery suitable for the achievement of a higher volume energy density has been selected in a battery structure required having a large capacity.
A rechargeable battery is constituted by a metallic collector having a negative active material layer formed on the surface (hereinafter referred to as negative plate), a separator retaining an electrolytic solution, and the other metallic collector having a positive active material layer formed on the surface (hereinafter referred to as positive plate), and it is necessary to perform electrical connection between a positive electrode terminal and a negative electrode terminal and an electrode group composed of the negative plate, the separator, and the positive plate.